Reversible one way clutch for wrench



Aug. 30, 1966 L. E. KiLNESS REVERSIBLE ONE WAY CLUTCH FOR WRENCH Filed June 22, 1964 INVENTOR. LUTHER E. KILNESS United States Patent 3,269,496 REVERSIBLE ONE WAY CLUTCH FOR WRENOH Luther E. Kilness, 211 E. Philadelphia St., Rapid City, S. Dalr. Filed June 22, 1964, Ser. No. 377,028 4 Claims. (Cl. 192-431) This invention relates to ratchet mechanisms and more particularly to ratchet mechanisms of the type employed in hand tools, suchas ratchet wrenches. This application is a continuation-in-part of application Serial No. 76,341, filed December 16,1960, and now abandoned.

One object of the invention is to provide a simple and inexpensive pawl control system.

Another object is to provide an efficient pawl spring requiring little space.

Still another object is the provision of a compact pawl spring which reverses the direction of the pawl action with limited angular movement of the pawl.

Other objects and advantages of the invention will be apparent from the description and drawing. In the drawmg:

FIGURE 1 is atop view of the head portion of a ratchet wrench illustrating the invention. Part of the top cover is shown as broken away to show pawl-shifting elements.

FIGURE 2 is a horizontal section of the wrench head taken on the line 22 of FIGURE 3.

FIGURE 3 is a vertical section of the wrench head.

FIGURE 4 is a diagrammatic view on an enlarged scale showing the pawl and cooperating ratcheting members.

FIGURE 5 is a detail view of the pawl spring on the same scale as in FIGURE 4.

The embodiment of the invention selected for illustration has a handle member terminating in an annular head 11. A rotatable member 12 is journaled in a circular opening 13 in the head by a circular series of ratchet teeth 14 on the rotatable member. The ratchet teeth have radially extending crests, which are closely fitted to the circular opening. The rotatable member is provided with a square projection 15 for receiving detachable sockets. The sockets are maintained in position by a spring-loaded ball 16 on the projection.

The top of the wrench is sealed by a cover plate 17, which is retained by an assembly screw 18. A bottom plate 19 pressed on the projection 15 seals the lower part of the wrench head. A retaining ring 20 is fitted to corresponding grooves in the head 11 and plate 19. The retaining ring is of the split type and has ends received in a recess 21 at the rear of the head. The recess 21 is large enough to permit access to the ring ends for compressing the ring ends for disassembly purposes.

A pawl chamber or recess 22 is formed in back of the head 11 and is open to the rotatable member 12. The sides of the recess form bearing surfaces for receiving the pawl thrust. The sides of the recess are inclined toward each other as they progress away from the rotatable member. A pawl 23 is contained in the recess. The pawl has an arcuate side having teeth 24 adapted to the ratchet teeth 14 on the rotatable member. All of the pawl teeth are used for both driving directions. The arcuate side of the pawl is shorter than the circumferential length of the recess along the envelope of the ratchet teeth 14 to permit limited circumferential movement of the pawl. The pawl has two sides extending from the arcuate side which are inclined or generally convergent toward each other in a direction away from the arcuate side. The converging sides of the pawl form bearing surfaces corresponding in inclination to the bearing surfaces of the recess 22 for transmitting the thrust of the pawl to the recess.

A pawl spring 25 directs the pawl in ratcheting engagement with the teeth 14 on the rotatable member. The ends of the spring are received in a hole 26 in the pawl and a hole 27, or emplacement, in the recess 22. The holes 26 and 27 are larger than the ends of the spring to permit angular movement of the spring ends in the holes. T he Spring is in a state of compression, and the compressional action between the spring ends exerts a force on the pawl for maintaining the pawl toward either selected bearing surface of the pawl recess.

With the wrench set for driving in a clockwise direction, the pawl will be in the position shown in FIGURES 2 and 4. The vector [1 in the enlarged view of FIGURE 4 shows the direction of force acting on the pawl from the spring 25. The vector b is directed at an acute angle to the pawl teeth surfaces on the upper part of the pawl which are not taking the load and causes the pawl to slide over a successive series of teeth 14 when the handle is turned counterclockwise for the back stroke. The action of spring 25 is sufficient in itself to maintain the ratcheting action of the pawl during the back stroke: that is, cause the pawl to slide over successive series of teeth 14 and keep the pawl in proximity to the bearing surface of the recess 22 receiving the pawl thrust. By positioning hole 27 closer to hole 26, so that the pawl spring ends are brought closer together, the vector 1; may be directed more toward the position taken by vector 0, which helps prevent an undesirable overlap of pawl teeth 24 with teeth 14 if no auxiliary guide is employed to align the pawl with teeth 14.

The pawl recess positioned at the junction of the wrench handle and wrench head is necessarily limited in size. FIGURE 1 shows the contours of a modern ratchet wrench of round-head design. FIGURE 2 shows the cross-sectional area of the pawl recess 22. Increasing the size of the pawl recess would weaken the wrench at the junction of the head and handle, and the size of the recess is therefore restricted. In order to take full advantage of the limited size of a pawl recess positioned at the junction of the handle and head, the pawl should have dimensions approaching those of the recess, and the pawl should be reversible with only a small movement from one bearing surface of the recess to the other.

Various pawl control systems have been developed to meet the above criteria. One example of such a control system is shown in my copending patent application Serial No. 58,408, filed September 26, 1969. This criteria has not been met, however, in prior art control systems for a wide-arc pawl which have a spring acting between the pawl and a fixed locus or emplacement of a passive nature positioned on the pawl-carrying member and in which the fixed locus or emplacement does not initiate any pawl action or shifting. The present invention is an improvement over this type of control system and is particularly suited for ratchet mechanisms having a pawl recess at the junction of the handle and head members.

An important feature of the invention is the combination of dimensional relationships and pawl controls which permit a pawl size approaching the size of the pawl, recess and enable the pawl to be shifted with small movement of the pawl. FIGURE 4 shOWs the dimensional relationships involved. By maintaining the distance across the ends of the pawl spring, shown as dimension A, small compared to the dimensions of the pawl, the travel dimension B, which is the circumferential distance between extreme pawl positions, may be within acceptable limits. Dimensions A and B are each less than dimension C, which is the maximum dimension of the pawl in a radial direction through the center of the pawl and is measured from the crests or apexes of the pawl teeth at the center portion of the pawl and extends to the back of the pawl as shown in FIGURE 4. In FIGURE 5 a further useful figure of merit may be seen. The dimension D of the pawl spring, which is the dimension of the resilient portion of the spring, is substantially less than the dimension C.

A shift plate 28 moves the pawl 23 from one bearing surface of the recess 22 to the other bearing surface. The shift plate is mounted on a concentric projection 29 on the rotatable member 12. The shift plate has an extension 30 on one side provided with surfaces 31 and 32 inclined toward each other to form V-shaped surfaces. The V- shaped surfaces engage pins 33 and 34 on the pawl. The spacing between the V-shaped surfaces is less than the spacing between the pins to permit free movement of the pin not engaged by the V-shaped surfaces.

The shift plate 28 may serve the sole function of shifting the pawl from one side of the recess to the other for determining the direction of ratchet driving. Once the pawl is shifted to either operative position, the pawl spring 25 can maintain the pawl in either selected position. The shift plate may, however, serve the added function of providing guidance for the pawl during the ratcheting motion. By providing a resilient bias for the shift plate, as hereinafter described, the V-sha-ped surfaces exert a resilient force on either pawl pin 33 or pawl pin 34. In the position shown in FIGURE 4, V-surface 31 exerts a force on pawl pin 33 in the direction shown by vector a. The combination of vectors a and b produces a resultant vector c which causes the pawl to slide along the bearing surface of the recess 22 and into engagement with teeth 14. Since the pawl is constrained to move along a direction deter mined by the movement of pawl pin 33 along the V-surface 31 and since the pawl spring 25 does not act to move the pawl in opposition to the force provided by the V-surface 31, the resultant motion of the pawl is a translational oscillatory motion along the bearing surface of recess 22 during the back stroke.

Manual control of the direction of ratchet driving is obtained by operation of a manual shift element consisting of a lever 35 mounted on the cover plate 17. A crank member 36 has a reduced portion secured with a press fit in a hole in the lever. A crankpin 37 extends from the bottom of the crank member and is entered in a hole 38 in shift plate 28. The hole in the shift plate is larger in diameter than the crankpin to permit angular movement of the shift plate. A spring 39 is placed between the concentric projection 29 and the crankpin. The spring is in a compressed state to provide a resilient bias on the crankpin and maintain the lever and associated shift plate in either selected position.

In operation, the lever 35 is selectively moved to either of two positions for determining the direction of ratchet driving. An indented section 40 on the cover plate 17 permits angular movement of the lever. FIGURE 1 shows the lever in a position corresponding to a clockwise driving direction. The pawl will then be in the position shown in FIGURE 2 during the driving cycle and will have an oscillatory motion against the adjacent bearing surface of the recess 22 during the back stroke. To reverse the above-described action, the lever is moved in a counterclockwise direction, which causes the shift plate 28 to move in a clockwise direction. The extension 30 on the shift plate is formed with hooked ends to catch the previously f-ree pawl .pin, in this case pin 34, and urge the pawl to the other bearing surface of recess 22. The pawl will then be in position for driving the work in a counterclockwise direction.

While a preferred embodiment of the invention has been shown and described, the invention is not limited to the specific embodiment used for illustration, but includes such modifications as are within the scope of the following claims.

What I claim is:

1. In a reversible ratchet wrench, the combination of a handle having a head member provided with a circular opening therein, a rotatable member journaled in the opening of said head member, one of said members having a circular series of radially extending ratchet teeth, the other of said members having a recess communicating with said ratchet teeth, a pawl carried in the recess, said recess having two bearing surfaces inclined toward each other in a direction away from said ratchet teeth, said pawl having an arcuate side having a series of teeth adapted to concurrent and reversible driving engagement with said ratchet teeth, said pawl having two generally inclined sides extending from the ends of said arcuate side converging toward each other in a direction away from said arcuate side, the inclined sides of the pawl being adapted to the bearing surfaces of said recess for transmitting the thrust of the pawl in both directions of driving, and control means for bringing the pawl into reversible ratcheting engagement with said ratchet teeth, said control means including a spring acting between the pawl and said other member, said other member having an emplacement for engaging said spring, said spring having one end retained by said emplacement on said other member so that movement of the pawl from one bearing surface of the recess to the other bearing surface of the recess reverses the direction of action of the spring to urge the pawl against either selected bearing surface of the recess, the maximum length of said spring in any operative position in the recess being less than the radial dimension of the pawl through the center of the pawl from the crests of the pawl teeth to the back of the pawl, whereby the reversal of the spring action may be effected with a minimum of motion of said spring.

2. In a reversible ratchet wrench, the combination of a handle having a head member provided with a circular opening therein, a rotatable member journaled in the opening of said head member, one of said members having a circular series of radially extending ratchet teeth, the other of said members having a recess communicating with said ratchet teeth, a pawl carried in the recess, said recess having two bearing surfaces inclined toward each other in a direction away from said ratchet teeth, said pawl having an arcuate side having a series of teeth adapted to concurrent and reversible driving engagement with said ratchet teeth, said pawl having two generally inclined sides extending from the ends of said arcuate side converging toward each other in a direction away from said arcuate side, the inclined sides of the pawl being adapted to the bearing surfaces of said recess for transmitting the thrust of the pawl in both directions of driving, and control means for bringing the pawl into reversible ratcheting engagement with said ratchet teeth, said control means including a spring having ends compressed between the pawl and said other member, one end of said spring engaging the pawl centrally of said pawl teeth, said other member having a passive emplacement receiving the other end of said spring, said spring being positioned between said pawl and said emplacement so that the movement of said pawl from one bearing surface of the recess to the other reverses the action of said spring and maintains the pawl selectively against either of said recess bearing surfaces, the dimension between the spring ends having a sufficiently small magnitude as to permit reversal of said pawl with a pawl movement of less extent than the dimension of the pawl in a radial direction through the center of the pawl from the crests of the pawl teeth to the back of the pawl, said control means further including shift means mounted on said other member engaging the pawl for directing the pawl from one bearing surface of said recess to the other.

3. In a reversible ratchet wrench, the combination of a handle having a head member provided with an opening therein, a rotatable member journaled in said opening, means for sealing the rotatable member in said opening whereby the said members may be protected from foreign particles, said rotatable member having a projection extending exteriorly of said sealing means for receiving work elements, one of said members having ratchet teeth formed along a cylindrical envelope, the other of said members having a recess open to said ratchet teeth, a pawl carried in the recess, said recess having two bearing surfaces converging toward each other and adapted, to receive the pawl thrust, said pawl having an arcuate series of teeth adapted to concurrent and reversible engagement with said ratchet teeth, and control means for urging the pawl into reversible engagement with said ratchet teeth, said control means including a spring having two ends arranged between the pawl and said other member, one end of said spring centrally engaging the pawl, said other member having a passive emplacement receiving the other end of said spring, said spring being compressed between the pawl and said emplacement, the compressional force between the ends of said spring maintaining the pawl against either selected bearing surface of said recess, said control means including manually operable means having a manual shift element positioned exteriorly of said sealed members operatively connected to the pawl for directing the pawl from one bearing surface of said recess to the other.

4. In a reversible ratchet wrench, the combination of a handle having a head member provided with a circular opening therein, a rotatable member journaled in the opening of said head member, said rotatable member having a peripheral series of ratchet teeth confronting said circular opening, said head member having a recess communicating with said ratchet teeth, a pawl carried in the recess, said pawl being smaller than the recess to permit radial and lateral movement of the pawl within the recess, said recess having two bearing surfaces converging toward each other in a direction away from said ratchet teeth and adapted to receive the thrust of the pawl for the two driving directions, said pawl having an arcuate side having a series of teeth adapted to driving engagement References Cited by the Examiner UNITED STATES PATENTS 893,097 7/1908 Reanis 8 l63 2,138,332 11/1938 Geisel 192-43.1 2,943,523 7/1960 Gray et al.

2,957,377 10/1960 Hare 192-43.2 X 2,972,919 2/1961 Stalkup 8163 3,019,682 2/1962 Hare 192-43 References Cited by the Applicant UNITED STATES PATENTS 966,597 8/1910 Reams. 2,554,990 5/ 1951 Kilness. 2,981,389 4/1961 Kilness. 3,044,591 7/ 1962 Kilness. 3,078,973 2/1963 Kilness.

DAVID J. WILLIAMOWSKY, Primary Examiner. 

1. IN A REVERSIBLE RATCHET WRENCH, THE COMBINATION OF A HANDLE HAVING A HEAD MEMBER PROVIDED WITH A CIRCULAR OPENING THEREIN, A ROTATABLE MEMBER JOURNALED IN THE OPENING OF SAID HEAD MEMBER, ONE OF SAID MEMBERS HAVING A CIRCULAR SERIES OF RADIALLY EXTENDING RATCHET TEETH, THE OTHER OF SAID MEMBERS HAVING A RECESS COMMUNICATING WITH SAID RATCHET TEETH, A PAWL CARRIED IN THE RECESS, SAID RECESS HAVING TWO BEARING SURFACES INCLINED TOWARD EACH OTHER IN A DIRECTION AWAY FROM SAID RATCHET TEETH, SAID PAWL HAVING AN ARCUATE SIDE HAVING A SERIES OF TEETH ADAPTED TO CONCURRENT AND REVERSIBLE DRIVING ENGAGEMENT WITH SAID RATCHET TEETH, SAID PAWL HAVING TWO GENERALLY INCLINED SIDES EXTENDING FROM THE ENDS OF SAID ARCUATE SIDE CONVERGING TOWARD EACH OTHER IN A DIRECTION AWAY FROM SAID ARCUATE SIDE, THE INCLINED SIDES OF THE PAWL BEING ADAPTED TO THE BEARING SURFACES OF SAID RECESS FOR TRANSMITTING THE THRUST OF THE PAWL IN BOTH DIRECTIONS OF DRIVING, AND CONTROL MEANS FOR BRINGING THE PAWL INTO REVERSIBLE RATCHETING ENGAGEMENT WITH SAID RATCHET TEETH, SAID CONTROL MEANS INCLUDING A SPRING ACTING BETWEEN THE PAWL AND SAID OTHER MEMBER, SAID OTHER MEMBER HAVING AND EMPLACEMENT OF ENGAGING SAID SPRING, SAID SPRING HAVING ONE END RETAINED BY SAID EMPLACEMENT ON SAID OTHER MEMBER SO THAT MOVEMENT OF THE PAWL FROM ONE BEARING SURFACE OF THE RECESS TO THE OTHER BEARING SURFACE OF THE RECESS REVERSES THE DIRECTION OF ACTION OF THE SPRING TO URGE THE PAWL AGAINST EITHER SELECTED BEARING SURFACE OF THE RECESS, THE MAXIMUM LENGTH OF SAID SPRING IN ANY OPERATIVE POSITION IN THE RECESS BEING LESS THAN THE RADIAL DIMENSION OF THE PAWL THROUGH THE CENTER OF THE PAWL FROM THE CRESTS OF THE PAWL TEETH TO THE BACK OF THE PAWL, WHEREBY THE REVERSAL OF THE SPRING ACTION MAY BE EFFECTED WITH A MINIMUM OF MOTION OF SAID SPRING. 